Propensity scores - A brief introduction for resuscitation researchers.

Propensity scores are commonly used in observational research. This article provides a brief introduction to propensity scores aimed for resuscitation researchers. We discuss the concept and calculation of the propensity score and how it can be used to adjust for confounding via regression adjustment, stratification, weighting or matching. The interpretation of these method is briefly discussed and the advantages and limitations of propensity scores are presented. Lastly, we provide some practical recommendations for the presentation of studies using propensity scores.